I just finished building a 6.5cm with zermatt origin action/26" proof ss prefit. I loaded up a few 5 shot groups with H4350 (36.0gr/36.5gr/37.0gr/37.5gr) and hornady 140gr eld match in once fired hornady 6.5cm brass (There's only 20rds through the barrel before shooting these groups). The shoulder was bumped back 1 thou. I shot the first 3 charge weights but didn't continue bc I noticed that all the fired brass had a scuff looking ring around them (It's not raised up or at least not enough to feel super noticeable) and that's not to be confused with the darker ring below that near the base from the resizing die. Recommended max charge weight is 40.0gr and i stopped at 37.0. Other than the rings the brass looks fine. Primers look good. Anyone know what would cause this mark? Does it mean something bad is happening or dangerous?